Orthogonal frequency division multiplexing (OFDM) is a frequency division multiplexing technique that is widely used in current communication standards, such as, for example, New Radio (NR), Long Term Evolution (LTE), and Wi-Fi. A receiver in a 5th Generation (5G) NR communication system is required to support mixed numerologies in which a base station (e.g., gNodeB) transmits OFDM signals with different subcarrier spacings (SCSs) and different OFDM symbol durations.
FIG. 1 is a diagram illustrating OFDM symbols for each of a desired 15 kilohertz (KHz) SCS numerology and an interfering 30 KHz SCS numerology. A desired data numerology 102 includes a desired OFDM symbol 106 and a desired OFDM symbol 108. An interfering data numerology 104 includes interfering OFDM symbols 110 through 116. As shown, two interfering OFDM symbols overlap a single desired OFDM symbol. Each OFDM symbol includes a cyclic prefix (CP) portion 118 and a non-CP portion 120.
At the receiver, in order to recover each of the different numerologies, a fast Fourier transform (FFT) operation is performed with a proper FFT size. However, after the FFT operation, the effect of an interfering data numerology on a desired data numerology may not be completely removed, and the interfering data numerology may still cause interference with the desired data numerology. Typical methods, such as, for example, receiver (Rx) filtering and Rx windowing (e.g., an overlap-add methodology), are unable to cancel the interference completely. Furthermore, for Rx filtering, a large filter length may be required depending on a frequency separation between the mixed numerologies.